US health authorities are on alert as cases of Chagas disease, originating from South America, are increasingly being detected in the United States. Cases have now been reported in at least eight states.
Researchers at the Centers for Disease Control and Prevention (CDC) are now about to categorize the infectious disease as endemic , meaning occurring regularly within an area or community.
This is not just a medical formality but a wake-up call: The disease would no longer be considered an imported tropical disease but regarded as a permanently present health risk in the US.
The proposed classification would have far-reaching consequences for monitoring, research and treatment.
Disease transmitted by bug’s bite
The disease is passed on by the Trypanosoma cruzi parasite, which is found in various predatory bug species. The insect acquired the nickname “kissing bug” because it often bites sleeping humans in the face, in particular its more thin-skinned parts, such as lips or eyelids.
It’s not the bite itself that is dangerous, but the feces of the bug that contain the pathogen. By scratching the wound or rubbing the eyes the parasite makes its way into the body. Less frequently, people are infected via blood transfusions, organ transplants or during a pregnancy from mother to child.
WHO warns of neglected danger
The disease was named after Brazilian doctor Carlos Chagas, who discovered it in 1907. By now, Chagas is no longer some exotic tropical disease. Through migration, blood transfusions and global trade routes Chagas also found its way to Europe and North America. According to estimates, there are some 6,000 infected people in Spain and several hundred thousand in the US.
The World Health Organization estimates that, worldwide, over seven million people are infected with the pathogen and that some 10,000 die each year as a result of the infection. The disease is particularly widespread in Latin America’s poor regions, which is why the WHO classifies it as a “neglected disease.” Due to new data from the US the potentially lethal “disease of the poor” is now increasingly receiving international attention.
What are the symptoms of Chagas disease?
The infection has two stages. Many of those affected don’t notice any symptoms during the first weeks or months after the infection. Some develop unspecific symptoms such as fever, fatigue or swellings next to the wound, typically an eyelid edema, a painless, one-sided swelling of the eyelid which is often accompanied by conjunctivitis. Afterwards, those ailments usually disappear again, but the parasite remains in the body.
After a lag period that can take years, the chronic phase of the infection can break out. This comes with has serious consequences. Myocarditis, permanent heart failure, or cardiac arrhythmia have been documented, as well as pathological enlargement of esophagus and colon. Up to 30% of those infected develop such complications.
The WHO warns that, without treatment, the disease can be life-threatening, primarily for babies, children or people with a weakened immune system.
How can Chagas disease be treated?
During the acute phase, the parasite can be detected microscopically in the blood. In later stages, antibody tests are the most important diagnostic tool.
So far, there is no vaccine. Treatment is based on two antiparasitic drugs, Nifurtimox and Benznidazole, which are particularly effective during the acute phase.
Both medications, however, can cause severe side effects and are not yet officially approved for treatment of the Chagas disease in the EU, for example. In the US, the drugs can usually be administered during inpatient treatment only. In chronic cases, the therapy just alleviates the symptoms; so far the disease can hardly be prevented.
Pets and wild animals can get infected too
Not only humans are sought-after victims: Dogs, cats, rats, armadillos and opossums are also considered important hosts.
Texas and California, in particular, are now increasingly reporting infected dogs, which indicates that circulation of the pathogen is already established in the south of the US.
How to protect against Chagas disease?
In order to prevent an infection, expert recommend strict protection against insects. In affected regions, nets treated with insecticide, the sealing of house walls and specific pes control can help.
For pets, veterinarians recommend medication which is also used against fleas and ticks. In many countries, blood donations are now routinely tested for the pathogen, in order to prevent an infection by blood transfusion.
This article was originally written in German.
